Injury due to falls in the elderly are a substantial health problem. Approximately one-third of community dwelling persons over 75 fall each year and one-fourth of those who fall sustain serious injuries. The long-term objective of this research is to use biomechanical experiments and analyses to learn what age-related changes in neuromuscular function may degrade safe balance recovery abilities during a fall. A recent study demonstrated that healthy elderly, compared to young, adults have significantly reduced abilities to arrest an ongoing forward fall with a single rapid step. In the proposed study, myoelectric signal analyses and biomechanical modeling will be used to test the working hypothesis that age-related differences in balance recovery abilities are due primarily to changes in muscle mechanics rather than in neural factors. The performances of 48 healthy young and 48 healthy elderly adults will be observed when each takes a rapid step(s) to recover balance following release from increasing angles of forward lean. The following specific hypotheses will be tested: 1. Age reduces abilities to recover balance during a forward fall, even when multiple steps are allowed. 2. Age and gender do not alter trunk or lower-extremity muscle pre-motor latencies, muscle sequencing or myoelectric activation levels in the balance-recovery tasks. 3. Healthy elderly adults develop significantly smaller peak joint torques and lower peak rates-of-torque development than healthy young adults in the balance-recovery tasks. Thus, the intent of the study is to identify neuromuscular factors which limit balance recovery abilities in older adults. Understanding of these factors will lead to earlier diagnoses of risk for fall injuries, improved therapeutic measures and more effective programs for fall prevention.